Police outside Denver responded to a shooting at Arapahoe High School on Friday. One student was injured and the suspect is now deceased, apparently of a self-inflicted gunshot wound. The gunman has been identified as Karl Pierson, 18, a student at the high school who asked for a teacher by name. The teacher, Tracy Murphy, a librarian and debate team coach, then exited the building, hoping to lure Pierson outside. Police have not elaborated on a possible motive other than to say that Pierson had a "confrontation or disagreement" with Murphy. One student, a 15-year-old girl, has been transported to a hospital with a gunshot wound and was listed in serious condition as of Friday night.